myocytes that survive in the infarcted heart
نویسندگان
چکیده
Myocytes that survive in the epicardial border zone of the healing canine infarcted heart provide the substrate for inducible reentrant ventricular arrhythmias. These myocytes have been shown to have altered Ca currents which could impact on Ca homeostasis in these i cells. Objective and Methods: To directly measure and compare intracellular Ca transients and cell shortening in myocytes dispersed from control noninfarcted hearts with those from epicardial border zone of 5 day infarcted canine hearts using the Ca sensitive indicator fura-2rAM. Studies were designed to determine and compare the effects of rate and premature stimulation on intracellular Ca Ž . in the two cell types. Results: Epicardial cells from noninfarcted hearts 1 exhibited an increase in amplitude of the fura-2 ratio with Ž . Ž . decreasing pacing cycle length CL , while cells from the infarcted heart showed the opposite effect; 2 showed more marked Ž . acceleration of relaxation of the Ca transient with decreasing CL than myocytes from the infarcted heart; 3 exhibited little or no post i Ž . rest potentiation in contrast to cells from the infarcted heart; and 4 showed a more rapid recovery during restitution protocols than cells from the infarcted heart. Cell shortening differences were also observed between cell populations in that most cells from the infarcted zone did not show any degree of cell shortening despite the reasonable intracellular Ca transient. Conclusions: The handling of intracellular Ca in myocytes that have survived in the epicardial border zone is very different from that of normal epicardial myocytes suggesting that there may exist marked heterogeneity in intracellular Ca handling in cells in the in situ healing infarcted heart. Electrophysiologic implications of these findings are discussed.
منابع مشابه
Two-photon microscopy of healthy, infarcted and stem-cell treated regenerating heart.
Two-photon excitation autofluorescence (produced in myocytes) and second-harmonic generation (produced mainly by collagen) allow label-free visualization of these two important components of myocardium. Because of their different emission wavelengths, these two signals can be separated spectrally. Here, we examine two-photon microscopy images of healthy, infarcted and stem-cell treated rat hear...
متن کاملEngineered heart tissue graft derived from somatic cell nuclear transferred embryonic stem cells improve myocardial performance in infarcted rat heart
The concept of regenerating diseased myocardium by implanting engineered heart tissue (EHT) is intriguing. Yet it was limited by immune rejection and difficulties to be generated at a size with contractile properties. Somatic cell nuclear transfer is proposed as a practical strategy for generating autologous histocompatible stem (nuclear transferred embryonic stem [NT-ES]) cells to treat diseas...
متن کاملEffect of ANG II on pHi, [Ca2+]i, and contraction in rabbit ventricular myocytes from infarcted hearts.
In this study we examined Na+/H+exchange activity, Ca2+transients, and contractility in rabbit ventricular myocytes isolated from normal and chronically (8-12 wk) infarcted left ventricles. Myocytes from infarcted hearts (post-MI myocytes) were isolated from the peri-infarcted region of the left ventricle. Intracellular pH (pHi) and Ca2+ concentration ([Ca2+]i) were measured with the fluorescen...
متن کاملAcute sleep deprivation preconditions the heart against ischemia/ reperfusion injury: the role of central GABA-A receptors
Objective(s): Central γ-aminobutyric acid (GABA) neurotransmission modulates cardiovascular functions and sleep. Acute sleep deprivation (ASD) affects functions of various body organs via different mechanisms. Here, we evaluated the effect of ASD on cardiac ischemia/reperfusion injury (IRI), and studied the role of GABA-A receptor inhibition in central nucleus of amygdala (CeA) by assessing nit...
متن کاملCardiac progenitor cell commitment is inhibited by nuclear Akt expression.
RATIONALE Stem cell therapies to regenerate damaged cardiac tissue represent a novel approach to treat heart disease. However, the majority of adoptively transferred stem cells delivered to damaged myocardium do not survive long enough to impart protective benefits, resulting in modest functional improvements. Strategies to improve survival and proliferation of stem cells show promise for signi...
متن کامل